The present invention relates to control systems for motor vehicle steering systems, and more particularly to a system and method including a dynamic feedforward feature for integrated control of the motor vehicle steering and brakes.
Unified or integrated chassis control systems have been proposed which control the brakes, steering, and suspension of a motor vehicle. The purpose of unified chassis control is to improve vehicle performance in all driving conditions by coordinating control of the chassis subsystems. Unified chassis control systems typically utilize a supervisory control concept that utilizes three fundamental blocks: a reference model, a state estimator, and a vehicle control. The vehicle control element normally incorporates a feedback control. This element computes control values by comparing actual states obtained from the state estimator with desired states from the reference model.
It is well known that when brakes are applied during a steering maneuver, a yaw rate error is induced. It such circumstances, the conventional chassis control systems are relatively slow to compensate.
The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof.
Disclosed herein in an exemplary embodiment is a control system for a steering system in a vehicle comprising: a reference model responsive to an operator input that computes desired states of the vehicle; a feedforward controller in operable communication with the reference model. The feedforward controller computes a first control value based on input from the reference model and based on at least one of: a lateral velocity, a rate of lateral velocity, a lateral acceleration, and a combination, wherein the combination includes a yaw rate with at least one of a lateral velocity, a rate of lateral velocity, and a lateral acceleration of the motor vehicle. The system also includes a means for affecting the steering system based on the first control value, the means in operable communication with the feedforward controller.
Also disclosed herein is a method of controlling a steering system in a vehicle comprising: computing a desired state of the steering system; and computing a first control value based on the desired states of the steering system. The first control value is also computed based on at least one of: a lateral velocity, a rate of lateral velocity, a lateral acceleration, and a combination, wherein the combination includes a yaw rate with at least one of a lateral velocity, a rate of lateral velocity, and a lateral acceleration of the vehicle. The method further includes affecting the steering system based on the first control value.
Further disclosed herein is a control system for a steering system in a vehicle comprising: a means for computing a desired state of the steering system; a means for computing a first control value based on the desired state of the steering system and based on at least one of: a lateral velocity, a rate of lateral velocity, a lateral acceleration, and a combination. The combination includes a yaw rate with at least one of a lateral velocity, a rate of lateral velocity, and a lateral acceleration of the vehicle. The system further includes a means for affecting the steering system based on the first control value.
Also disclosed herein in yet another embodiment is a storage medium encoded with a machine-readable computer program code, the computer program code including instructions for causing a controller to implement the above mentioned method for controlling a steering system in a vehicle.
Further disclosed herein in yet another embodiment is a computer data signal, the data signal comprising code configured to cause a controller to implement the abovementioned method for controlling a steering system in a vehicle.
The present invention will now be described, by way of an example, with references to the accompanying drawings, wherein like elements are numbered alike in the several figures in which:
FIG. 1 is a simplified block diagram of a vehicle control system according to an exemplary embodiment;
FIG. 2 is a block diagram a block diagram representation of a control system including a reference model and the dynamic feed forward control system using a multi-order reference model; and
FIG. 3 is a flow chart depicting an exemplary embodiment of the methodology for computing dynamic feedforward control including blending;
FIG. 4 is a flow chart depicting an exemplary embodiment of the methodology for computing closed loop control with pole placement;
FIG. 5 is a flow chart depicting an exemplary embodiment of the methodology for computing throttle scheduling; and
FIG. 6 is a flow chart depicting an exemplary embodiment of the methodology for computing velocity blending of an exemplary embodiment.